Nylon composition having enhanced dyeability



eries of the orifices in the spinneret.

3,296,216 NYLON COMPOSITION HAVING ENHANCED .DYEABILITY Rupertu :J.. .Snooks, Jri, Gulf Breeze, Fla., assiguor to Monsanto. Company, St. Louis, Mo., a corporation of Delaware -NODrawing. Filed Apr. 16, 1964, Ser. No. 360,433

.5 Claims. (Cl. 260-78) This application is a continuation-in-part application of application Serial No. 307,315, filed September 9, 1963.

.This invention relates to the preparation of nylon polymers hav'in'g enhanced ability to receive dyes; More 'particularly, this invention relates to nylon-66 polymer con- ;taining additiveswhich render the polymer more receptive to dyes: and to a method of making such polymer,

' UnitedStates Patent 'ice source such as a flashlight at an angle onto the bundle of filaments moving from the spinneret through the spinning chimney. For a given set of spinning conditions, the intensity of the light reflectance should remain substantially uniform in order to produce yarn of uniform physical properties. When variations occur in the light reflectance, non-uniformity in physical properties in the yarn results.

It is an object of the present invention to provide a new and useful polymer having improved depth of dyeing.

It is another object to provide a new and useful nylon- 66 polymer having improved dyeability by the presence therein of a co'mbinationbf additives;

as; well as to a method of shaping such polymer into textile structures and the like.

Yarns made from nylon-66 polymer have gained wide acceptance in the textile trade because of their many desirable physical properties. 66 is prepared by polycondensing adipic acid and hexa- .methylenediamine. The resulting polymer does not have as good a dye affinity as some of the other specific nylon polymers. .1 Therefore, in order to increase the utility of nylon-66 for use in the manufacture of a more general purpose filamentary material, much research effort has presents certain problems in the manufacture of filaments meltlspun therefrom. For example, when nylon-66 containing hexarnethylene diammonium phenylphosphinate as awpolymer additive for the accomplishment of deeper dyeing is melt spun. into filaments, excessive foaming and increased processing time in the polymer forming stage are experienced. Furthermore, it has been observed that in the formation of filaments there is a greater tendency for buildup of polymeric incrustations around the periph- The presence of such incrustations gives rise to a very bothersome problem referred to as spinneretdrips. .In addition, yarn melt spun. from. nylon-66 containing the phenylphosphinate compound has poor drawing performance in that breakage of; the individual filaments and complete threadline, as well as extraneous wraps around the drawing roll, is experienced during the molecular orientation of the yarn.

It has been: observed that N-aminoethyl piperazine when i added to nylon-66 increases the depth to which such polymer can be colored by said dyes; Unfortunately, the making of nylon-66 polymer containing the piperazine compound alone and the forming of filaments give rise to certain notable disadvantages, i.e., increased spinneret drips, poor drawing performance, reduced tenacity and severe discoloration of yarn melt spun therefrom. It hasbeen found that adding the combination comprising a small amount of phenylphosphinic acid and a small amount of N-aminoethyl piperazine to nylon-66 enables one to maintain the increased dyeing depth of such polymer containing the additives individually Without the justmentioned attending processing problems. Unfortunately, the use of the binary system of additives gives rise to an undesirable variable luster. during spinning yarn made therefrom. In other words, yarn spun from nylon- 66} containing a small amount of phenylphosphinic acid and a :small amount of N-aminoethyl piperazine exhibits variations in luster: during spinning. Variations in luster during .spinningis observed by directing light from a As iswell known, nylon- It is a further object to provide a structure shaped from nylon-66 polymer having increased dye affinity by the presence therein of a combination of additives.

It is yet another object to provide a method for preparing nylon-66 polymer capable of being dyed deeper.

It is still another object to provide a method of preparing deeper dyeing nylon-66 textile yarn.

The objects of this invention are accomplished by incorporating in nylon-66 a particular ternary dye-enhancing combination of additives. The combination comprises a small amount of phenylphosphinic acid, a small amount of N-aminoethyl piperazine, particularly N-(2- aminoethyl) piperazine, and a small amount of caprolactam. The nylon is prepared by forming a mixture of a nylon-forming monomeric component and the particular dye-enhancing combination of additives and by thereafter heating the resulting mixture at nylon-forming temperatures for a suflicient time to polycondense the nylon-forming component to the desired degree of poly condensation. The nylon-forming component ordinarily is the salt of hexamethylenediamine and adipic acid. The resulting nylon-66 polymer is worked or shaped into textile structures and the like by conventional procedures.

The amount of phenylphosphinic acid incorporated in the nylon polymer is usually about 0.05-1.0 percent based on the weight of the resultant nylon polymer. By employing the phosphinic compound much below 0.05 percent, one does not obtain the desired increase in dyedepth of the polymer. Not substantially exceeding 1.0 percent phenylphosphinic acid in the additive system enables one to avoid excessive forming in the polymer forming stage. A more preferred concentration of the phosphinic compound is in the range of 0.1 and 0.5 weight percent.

The amount of N-aminoethyl piperazine incorporated in the nylon polymer will generally be in the same ranges specified for the phosphinic compound. That is to say, the preferred amounts of piperazine compound will be about 0.05-1.0 percent based on the weight of the poly mer with the more preferred amounts ranging from 0.1- 0.5 percent. By employing the piperazine compound in an amount much below 0.05 percent, one does not obtain the desired increase in dye-depth of the polymer. Not substantially exceeding 1.0 percent piperazine compound in the additive system enables one to avoid excessive spinneret drips.

It has been found that the addition of about 0.5-12.0 weight percent E-caprolactam to the polymer additive formulation including phenylphosphinic acid and N- aminoethyl piperazine mitigates or eliminates variable luster in filaments made from the polymer. Furthermore, the addition of caprolactam gives increased acid dyeability sufficient to permit a reduction in the total weight of the additives necessary for a given dye depth. This reduction of the amount of additives effects an improvement in drawtwisting performance of yarn made therefrom. A more preferred concentration of caprolactam is in the range of 0.7-9.0 weight percent.

The most useful nylon-66 polymers obtained are high molecular weight materials having an intrinsic viscosity of 0.4 or above. The high molecular weight nylon having an intrinsic viscosity of 0.7-1.3 advantageously can be formed into textile grade filaments, fibers, films, and the like.

Intrinsic viscosity can be ascertained by first determining the specific viscosities of a series of solutions of the nylon polymer. Then, these data are plotted on a graph and the intrinsic viscosity calculated therefrom. Specifically, a series of polymer solutions are prepared in concentrations, for example, of 0.1, 0.2, 0.3, 0.4 and 0.5 percent by weight. A 100 series viscometer tube is used; and the efilux time in seconds at 25 C. is determined for each solution and the solvent employed. Specific viscosity is then determined as follows:

effiux time of solution efilux time of solvent A graph is made in which N percent concentration is plotted against percent concentration. A straight line is drawn through the points. By extrapolating the line to zero concentration, the intrinsic viscosity is determined, i.e., the point at which the extrapolated line crosses the N /percent concentration axis is taken as the intrinsic viscosity.

The ternary combination of dye-enhancing additives can be incorporated in nylon-6 6 in various ways. One preferred way is to admix the ingredients of the combination of additives with nylon-66 salt before polycondensation. However, incorporation of the additives together or separately to the nylon-forming reactants at any time during the polycondensation can be made.

The nylon polymers having the combination of dyeenhancing additives incorporated therein can be shaped or worked into various forms. For example, the polymer can he melt spun into yarns, bristles, filaments, films and the like. Articles can be molded from the nylon; surfaces can be coated therewith.

For a more detailed description of the present invention, reference is made to the following specific examples. The examples are intended merely to be illustrative and not limitative. In the examples, all parts and percentages are by weight unless otherwise indicated.

Example I First, an aqueous solution of hexamethylene diammonium phenylphosphinate was prepared. To do this, hexamethylenediamine was gradually added to an aqueous solution containing 25.3 weight percent benzene phosphinic acid while mixing in an amount to raise the pH of the solution to 6.3.

A stainless steel autoclave adapted for bath polycondensation of nylon-6 6 was filled with nitrogen gas and was charged with an aqueous solution containing 75 percent by weight of the adipic acid salt of hexamethylenediamine (nylon-66 salt). The temperature of the charge was 150 C., and the pressure in the autoclave was 150 p.s.i.g. Immediately after the salt change was completed an amount of the prepared hexamethylene diammonium phenylphosphinate was added to the autoclave such that the ultimate polymer would have about 0.75 percent phenylphosphinic acid.

The contents in the autoclave then were heated quickly to a temperature of 200 C. under 250 p.s.i.g. pressure at which time a small amount of an aqueous slurry containing 30 weight percent TiO 'delustrant was added such that the ultimate polymer contained 0.3 percent TiO Heating of the contents was continued until the nylonforming material in the autoclave reached a temperature of 243 C. At this stage bleeding off of water vapor was begun to reduce the pressure in the autoclave to atmospheric pressure. During this pressure reduction the polymer temperature gradually was increased to 270 C. Upon completion of the polycondensation reaction, the polymer was extruded in the form of a ribbon onto a casting wheel where it was quenched with water. Thereafter, the ribbon was cut into chips or flakes suitable for forming into filaments by the use of a. heated grid spinning apparatus.

Polymer waste due to discoloration and formation of foam during the extrusion of the polymer averaged 2.8 percent. On the other hand, waste for like polymer not containing the phosphinate additive averaged 0.5 percent.

The nylon chips containing the additive were then melted in a steam atmosphere in a grid spinning apparatus and spun by conventional melt spinning into a total denier-34 filament yarn at a takeup rate of 1600 y.p.m. Spinning was continued for two weeks. The formation of spinneret drips was observed and compared to those observed when yarn not containing the phosphinate additive was produced. During the spinning of polymer containing the additive 18 spinneret drips per machine day were observed whereas during the spinning of polymer containing no additive only 3 spinne-ret drips per machine day were observed. Low luster unit failures per machine day for spinning additive-containing polymer were 3.7 as compared to only 1.5 for polymer without additive.

The substantially unoriented yarn containing the phosphinate additive was then cold-drawn and taken up in package form using a conventional d-rawtwisting machine. The draw ratio employed was 2.4. Drawing performance of this yarn was observed and compared to similar yarn containing no phosphinate additive. Results showed that the test yarn had 0.13 breaks and wraps per pound while the control yarn'exhi bited only 0.035 breaks and wraps per pound.

This example illustrates the inferior polymer spinning and drawtwisting performance of yarn containing a small amount of hexamethylene diammonium. phenylphosphinate to enhance the dyeability thereof.

The yarn containing the additive was knitted into tricot and circular knit fabrics. These fabrics were scoured and dyed in acid, dispersed, and premetallized dyes. The results of the dyeings showed significantly increased dye rates of the additive-containing yarn with the acid and premetallized dyes with essentially no change in dispersed 'dye rates.

Example 11 The adipic acid salt of hexamethylenedia-mine was polycondensed following the procedure of Example I adding an aqueous solution containing 13.6 weight percent phenylphosphinic acid and a second aqueous solution containing 13.6 weight percent N-(Z-aminoethyl) piperazine in an amount such that the ultimate polymer lhad equal amounts of each additive and a total additive content of 0.75 weight percent. Also, the same amount of TiO as used in Example I was added during polycondensation. Chips of the resulting nylon were formed as described in the first example. Foaming and discoloration of the polymer were observed to be virtually eliminated by the use of the combination of additives with no more polymer waste than that of the nylon polymer containing no additive.

The nylon chips of this example were then melted in a steam atmosphere and spun into a 70 denier-34 filament yarn by the use of a heated grid spinning apparatus at a take-up rate of 1500 y.p.m. Spinning was continued for a period of three days. The frequency of spinne-ret wipes was the same as that of Example I. No drips occured during the three days that polymer of this example was spun into yarn. The incidence of luster variation, however, was excessive.

'I he undrawn yarn was then given an orientation stretch of 2.74 times. Drawing performance of this yarn was much superior to yarn containing hex'amethylene diammonium phenylphosphinate additive alone, and averaged only 0.090 breaks and wraps per pound of yarn.

It can be seen from this example that the combination of substantially equal amounts of phenylphosphinic acid and N-aminoethyl piperazine significantly improves deepdye nylon-6 6 polymer formation and drawtwist performimprovement in drawtwisting performance. of this example averaged only 0.070 breaks and wraps ance of yarnmadetherefrom. But, luster variation was found. to be. undesirably high.

The ryarn ofthis example and the yarn of Example I containing only. the phosphinate additive were knitted into tricot fab'rics. When both fabrics were dye-d using acid,

3 dispersed and premet-allized dyes, it was found that the falbricsexhibited comparable dye depths.

Example 111 The i adipic. acid salt of heXaanethylenediam-inc was p'olycondensed following the procedure of Example I adding phenylphosphinic acid and N-(Z-arninoethyl) piperazine in amounts such that the ultimate polymer had equal amounts of each additive and a total additive content of 0.75 percent. Also, to the nylon-forming material E-caprolactam was, added in an amount that the ultimate polymer had oneweight percent of this additive. Otherwise, the procedure: of Example 11 was followed exactly. It

wasfound that the sameiexcellent polymer formation and drawtwistperform-ance of yarn made therefrom resulted.

yarn of thisqexamp-le visually dyed more deeply than that of Example. II) Furthermore, yarn of this example accepted a higher Ibullcwhen textured by the stulfer box procedure than nylon-.66 yarn when basic dyes were employed. 1:

Example IV Using the polymer: formulation of Example III, the amount of phenylphosphinic acid was reduced to the I point where fabric made from the resulting yarn dyed comparablyto the fabric of Example II. It was found that .to accomplish this the weight percent of phosphinic compound could be reduced from 0.37 to 0.25. This reduction in phosphinic additive content resulted in an The yarn per pound.

Example V The adipic acid salt of hexamethylenediamine was polycondensed following the procedure of Example III,

adding additives in such amounts that the ultimate polycontaining the, additive were then melted in a steam atmospherein a grid spinning apparatus and spun by conventional melt spinning into a 1230 total denier-68 filament yarn at a take-up rate of 300 y.p.m. The yarn exhibited no. luster variation and its texturizcr performance. wastexcellent, only 0.012 interruptions per pound.

Thettexturing procedure employed was the hot-draw gear-:quenchgimethod disclosed in US. Patent 3,024,517.

When dyed with acid and premetallized dyes, this textured yarn dyed ;to. :a colormaster value of 135 units.

The yarn of Example IV had a colormaster value of only 55 i units.

Similar improvements were-found when nylon polymer containing the combination of additives of the present invention was made employing conventional continuous polymerization apparatus including an evaporator, reactor, flasher and finisher.

Thus, it is seen that the present invention provides numerous advantages. Among these is the imparting of deeper dyeing characteristics to nylon yarn. By the use of the combination of additives herein, one is able to utilize the dye-enhancing property of phenylphosphinic acid with less loss of polymer due to foam formation and polymer deterioration. In addition, melt spinning in regard to incidence of luster variation and drawtwisting in regard to the number of breaks and wraps per pound of yarn is greatly improved as compared to yarn containing only hexamethylene diammonium phenylphosphinate or phenylphosphinic acid in combination with N-aminoethyl piperazine.

As many different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the above-disclosed specific embodiments except as defined in the following claims.

What is claimed is:

1. A polyhexamethylene adipamide filament having incorporated therein on a weight basis:

(a) about 0.051.0 percent phenylphosphinic acid,

(-b) about 0.05-1.0 percent N-(Z-aminoethyl) piperazine, and

(0) about 05-120 percent E-caprolactam.

2. A polyhexamethylene adipamide filament having incorporated therein on a Weight basis:

(a) about 0.1-0.5 percent phenylphosphinic acid,

(b) 01-05 percent N-(Z-arninoethyl) piperazine, and

(c) 0.7-9.0 percent E-caprolactam.

3. A polyhexamethylene adipamide filament having incorporated therein on a weight basis:

(a) 0.75% phenylphosphinic acid,

(b) 0.25% N-(Z-aminoethyl) piperazine, and

(c) 9.0% E-caprolactam.

4. A polyhexamethylene adipamide filament having incorporated therein on a weight basis:

(a) 0.375% phenylphosphinic acid,

(b) 0.375% N-(2-aminoethyl) piperazine, and

(c) 1.0% E-caprolactam.

5. A polyhexamethylene adipamide filament having incorporated therein on a weight basis:

(a) about 0.051.0% phenylphosphinic acid,

(b) about ODS-1.0% N-aminoethyl piperazine, and

(c) 0.5-12.0% E-caprolactam.

References Cited by the Examiner UNITED STATES PATENTS 2,252,555 8/1941 Garothers 260 -78 2,324,936 7/1943 Kroeper et al 260--78 2,359,833 10/1944 Faris 26078 2,904,536 9/1959 Reith 260-78 3,235,534 2/1966 Brinkman et a1 26078 WILLIAM H. SHORT, Primary Examiner. H. D. ANDERSON, Assistant Examiner. 

1. A POLYHEXAMETHYLENE ADIPAMIDE FILAMENT HAVING INCORPORATED THEREIN ON A WEIGHT BASIS: (A) ABOUT 0.05-1.0 PERCENT PHENYLPHOSPHINIC ACID, (B) ABOUT 0.05-1.0 PERCENT N-(I-AMINOETHYL) PIPERAZINE, AND (C) ABOUT 0.5-12.0 PERCENT E-CAPROLACTAM. 